In shock wave therapy, kidney or gall stones (concrements) are disintegrated by means of focused shock waves. Other forms of shock wave therapy are used for the treatment of pain, the treatment of closed vessels, the treatment of the cardiac muscle, in a corresponding target area. The shock wave source generally has a focus which is determined by its geometry. For example, the focus can be generated through a lens.
In order to direct the focus of the shock wave source at the concrement or target area, it is necessary to locate the concrement or corresponding structures of the target area. Location information using both X-rays and ultrasound is known.
For example, German Patent DE 203 15 924 U1 discloses a shock wave source that is known where an ultrasound converter is connected with the shock wave source in a specified geometric arrangement, so that the concrement can be located with the ultrasound converter. Because of the fixed geometric relationship, the position of the focus can be indicated by a marker, such as a cross, in the ultrasound image. Therefore, during image monitoring, the concrement or target area can be moved in relation to the focus until alignment is achieved.
However, in German Patent DE 203 15 924 U1, the physical shock wave focus is not proven and displayed using measurement technology. Therefore, incorrect adjustment of the mechanical coupling of the shock wave source can cause deviations between the displayed and actual focus positions. This incorrect adjustment would lead to ineffective treatment with an increased risk of side effects. In addition, it cannot be directly detected whether the shock wave is reaching the focus to a sufficient degree. Faulty acoustic coupling between the shock wave and the body to be treated can weaken the shock wave energy applied. Furthermore, faulty acoustic coupling can occur between the shock wave and strong reflections on, for example, ribs located above the target organ.
It is known from German patent DE 37 03 335 C2 that an ultrasound receiver unit in the form of a PVDF foil can be provided. This ultrasound receiver unit can receive a reflected echo which occurs at a concrement when the shock wave pulse hits the concrement. The disadvantage of this is that image production is only possible with application of a shock wave pulse, but not beforehand, to allow the shock wave source to be adjusted. Furthermore, this method requires a shock wave therapy device to meet certain structural preconditions, such as the existence of a lens.
European patent EP 0 460 536 A1 describes a lithotripter in which no imaging is used to align the focus and the concrement. Instead, a piezoelectric shock wave source is used to generate a weak ultrasound pulse and the echo is received on a time-resolved basis, so that it can be concluded from a strong echo that the position of the focus coincides with the concrement. The disadvantage of this method is that no direct image production is possible, although this is a major advantage for carrying out lithotripsy, since direct image production can be used to determine the shape, size and state of disintegration of the concrement. In addition, presenting the surrounding anatomy is important for safe treatment, since the target can only be clearly identified in this way, and adjacent risk structures can be protected.
Furthermore, an alignment of a B image with a speed image is known from German patent DE 4113697 A1. Movements of the concrement, for example, or cavitation blistering triggered by the shock wave can be detected in this way. However, the disadvantage is that movements only occur in the case of cavitations which are, in themselves, unwanted, or only when the concrement is hit by the shock wave. Otherwise, no movements can be detected and the method is no longer helpful.